CHEMISTRY · Single correct · AP · Chemistry · Chemical Reactions · Chemical Reactions
Problem
A student has only a digital balance, adhesive tape to seal containers, and pH paper. The student must decide whether mixing solid NaHCO3 with 25 mL of 1.0 M HC2H3O2 produces a chemical or a physical change. Which data set, collected in a single 3-minute trial, would most directly allow the student to make that determination?
(a) pH of the acid solution measured before and after adding NaHCO3.
(b) Mass of a sealed container recorded before and after mixing NaHCO3 and HC2H3O2 inside.
(c) Mass of an open beaker recorded before and after mixing the reactants in air.
(d) Colour of pH paper held just above the mixture at 30\,\text{s} intervals.